I got the dac operational today. The pictures will follow.

At the moment it works in the hardware mode, ie it jumps into some default state. I cannot set up filters etc. It is configured to accept usb.
When arduino comes, or rather I have a display that fits in my enclosure I should be able to have volume control, set up filters. I will try to add an spdif input. But I am running ahead of myself. Maybe I will stop here as there is so much music available through usb...
The nice thing would be to feed i2s signal from the RPi, but this apparently does not work with different sampling rates and bit depths.

Btw I had a wonderful evening (still more to come, but now with headphones using Pelerano's Zen head amp) listening to NPR Tiny desk concerts with Hillary Hahn and Yo Yo Ma and many others...